Abstract:The main causes of the browning changes of medlar wine during fermentation and aging were investigated by determination of changes in polyphenol oxidase (PPO) and peroxidase (POD) activities, the discussion of variation rules of the total phenol, flavonoids, 10 monomer phenols, VC and the 5-Hydroxymethyl furaldehyde (5-HMF), as well as the analysis of browning degree changes of the Maillard reaction. The results showed that a large amount of monomers phenol rutin, chlorogenic acid, ferulic acid, p-hydroxybenzoic acid and p-coumaric acid in the zymotic fluid which greatly affected the degree of browning. At meanwhile, the oxidative degradation of VC and the Maillard reaction of sugars and amino acids also participated in the browning. In conclusion, enzymatic browning as well as non-enzymatic browning co-existed in the process of fermentation. The main cause of the browning was the participation of phenolic substances in both enzymatic and non-enzymatic browning reactions.
